The invention relates to a multi-stage vacuum pump and a stator of such a pump.
Vacuum pumps are used for example in the manufacture of semiconductors or flat panel displays. During manufacture a processing gas is released into a chamber. It is often desirable to maintain a low pressure in the chamber whilst at the same time providing a relatively high flow of gas through the chamber. A typical pumping arrangement for achieving both low pressure and relatively high through put is to combine a booster pump with a backing pump. The backing pump may be a multi-stage pump principally provided to produce a high compression ratio for generating a low pressure in the chamber. The booster pump is usually a single stage pump with a high capacity for producing relatively high gas flow. The booster pump generates only a small amount of compression.